Journal Article

The comoving infrared luminosity density: domination of cold galaxies across 0 < <i>z</i> < 1

N. Seymour, M. Symeonidis, M. J. Page, M. Huynh, T. Dwelly, I. M. McHardy and G. Rieke

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 402, issue 4, pages 2666-2670
Published in print March 2010 | ISSN: 0035-8711
Published online March 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.16083.x
The comoving infrared luminosity density: domination of cold galaxies across 0 < z < 1

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In this paper, we examine the contribution of galaxies with different infrared (IR) spectral energy distributions (SEDs) to the comoving IR luminosity density (IRLD), a proxy for the comoving star formation rate (SFR) density. We characterize galaxies as having either a cold or hot IR SED depending on whether the rest-frame wavelength of their peak IR energy output is above or below 90 μm. Our work is based on a far-IR selected sample both in the local Universe and at high redshift, the former consisting of IRAS60 μm-selected galaxies at z < 0.07 and the latter of Spitzer70 μm selected galaxies across 0.1 < z≤ 1. We find that the total IR luminosity densities for each redshift/luminosity bin agree well with results derived from other deep mid-/far-IR surveys. At z < 0.07, we observe the previously known results that moderate luminosity galaxies (LIR < 1011 L) dominate the total luminosity density and that the fraction of cold galaxies decreases with increasing luminosity, becoming negligible at the highest luminosities. Conversely, above z= 0.1, we find that luminous IR galaxies (LIR > 1011 L), the majority of which are cold, dominate the IRLD. We therefore infer that cold galaxies dominate the IRLD across the whole 0 < z < 1 range, hence appear to be the main driver behind the increase in SFR density up to z∼ 1 whereas local luminous galaxies are not, on the whole, representative of the high-redshift population.

Keywords: galaxies: evolution; galaxies: starburst; infrared: galaxies

Journal Article.  3703 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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